On Sun, 17 Apr 2022 at 10:45, Sergey Nazaryev sergey@coolautomation.com wrote:
So I think the right place to call usb_gadget_initialize is probably before registering the acm gadget function into acm_stdio_start(). Can you try this? and submit a follow_up fix patch if working?
It's required for `usb_gadget_initialize` to provide a "USB controller index" as an argument. It's pretty obvious how to do it in "interactive world" (e.g. to ask user for this number via CLI, like it was in commands mentioned in my previous message) but in our case we need to provide this number in non-interactive manner.
There is not an elegant solution with hardcoding '0' as a controller index like it was done in `ether` gadget [1], but it seems that it was a temporary fix ("This is a preparatory work for DM support for UDC drivers") that occasionaly became a permament solution.
So, that's why I suggested to add a new subcommand to `usb` for OTG initialization: in my opinion, it's better to require an explicit call of something like `usb otgstart 0` than hardcoding a '0' into the code. One more option is to add a new environment variable to explictly specify a controller index, and read this variable from all places when it requires.
P.S. I already put `usb_gadget_intiialize(0)` to my board code, and ACM gadget started working; so the remaining problem is only to decide where is the best place for this call.
Yes, but whatever the solution, we also need to know the controller index from gadget driver, since we need it for usb_gadget_handle_interrupts(index). So an env or global variable would be at least a good start.
Regards, Loic